Roberto Horn Pereira

Bio: Roberto Horn Pereira is an academic researcher from The Coca-Cola Company. The author has contributed to research in topics: Refrigerant & Heat exchanger. The author has an hindex of 7, co-authored 22 publications receiving 170 citations. Previous affiliations of Roberto Horn Pereira include Whirlpool Corporation.

Non-adiabatic capillary tube flow with isobutane

Abstract: This work reports the results of an experimental study on concentric capillary tube–suction line heat exchangers commonly used as expansion devices in household refrigerators and freezers. Heat exchanger performance (mass flow rate and suction line outlet temperature) with the hydrocarbon HC-600a was experimentally evaluated for a range of heat exchanger geometries and operating conditions. The tests were planned and performed following a statistically based methodology. Based on the resulting database empirical correlations were developed to predict the refrigerant mass flow rate and the suction line outlet temperature.

Experimental Study on Lateral Capillary Tube-Suction Line Heat Exchangers

Abstract: This work presents an experimental approach to study the refrigerant flow through capillary tube-suction line heat exchangers. Lateral heat exchanger performance with refrigerant HFC-134a was experimentally evaluated for a range of heat exchanger assemblies and operating conditions typically found in household refrigerators and freezers. Based on the resulting performance data base, the influence of both the operating conditions and heat exchanger geometry on the refrigerant flow were examined. It was also shown that the experimental data base is in close agreement with the predictions of a numerical model available in the literature.

Experimental Evaluation of the Heat Transfer Through the Walls of Household Refrigerators

Abstract: This work presents an experimental analysis of heat transfer paths from the surroundings to the interior food compartment of a 230 liters all refrigerator under closed door conditions. The overall refrigerator thermal conductance was determined from conventional reverse heat loss rate measurements as well as from unconventional measurements taken with specially manufactured heat flux sensors. The heat transfer rate through each of the various pathways (walls, door, gasket, etc.) was also quantified.

EXPERIMENTAL STUDIES ON NON-ADIABATIC FLOW OF HFC-134a THROUGH CAPILLARY TUBES

Abstract: This paper discusses results from an experimental work on concentric capillary tube-suction line heat exchangers commonly used as refrigerant control devices in household refrigerators and freezers Heat exchanger performance with the hydrofluorcarbon R-134a was experimentally evaluated for a range of heat exchanger geometries (diameter and length of the capillary tube, length and position of the heat exchanger) and operating boundary conditions (condensing pressure and subcooling) The results provided enough data to study the influence of the independent variables (geometry and operating conditions) on the dependent variables (refrigerant mass flow rate and temperature profiles)

An experimental analysis of adiabatic capillary tubes

Abstract: This paper presents an experimental study on capillary tubes commonly used as expansion devices in household refrigerators and freezers. The paper discusses the details of the experimental facility that has been developed and used to generate reliable experimental data within an acceptable level of uncertainty. The investigations include the effect of capillary length, capillary diameter, refrigerant subcooling, condensing pressure and type of refrigerant on the mass flow-rates through the capillaries. The experiments were performed with three refrigerants, namely CFC-12, HFC-134a and HC-600a, and at different condensing pressures and levels of subcooling under choked flow conditions. Eight capillaries with different combinations of lengths, diameters and tube roughnesses were used, and extensive data (exceeding 1000 sets) were collected. A conventional, dimensional analysis was performed to derive correlations to predict the mass flow rates for different refrigerants. The predictions from the developed correlations are found to be in good agreement with the measured data and other studies in the literature. The correlations would be very valuable in the design exercise of capillary tubes for alternative refrigerants in future.

Enhancements in domestic refrigeration, approaching a sustainable refrigerator – A review

Abstract: The refrigerator is an essential domestic appliance product and is available worldwide. Additionally, the technologies on which the majority of refrigerators are based involve high energy consumption, and environmental deterioration due to the type of energy input and the use of certain work fluids. Therefore, how refrigerators work is of great interest, and in recent years the development of diverse research in this field has intensified. As a consequence, in this article we present an exhaustive review of the research with the greatest impact on domestic refrigeration, based on vapor compression such as modeled, thermal stratification, control, environmentally innocuous refrigerants, thermal isolation, and hybrid systems, among others. Based on the above, we present the principal trends in this area, of interest to both industry and researchers.

An homogeneous model for adiabatic capillary tubes

Abstract: This paper presents a homogeneous two-phase flow model, CAPIL, which is designed to study the performance of adiabatic capillary tubes in small vapour compression refrigeration systems, in particular household refrigerators and freezers. The model is based on the fundamental equations of conservation of mass, energy and momentum that are solved simultaneously through iterative procedure and Simpson's rule. The model uses empirical correlations for single-phase and two-phase friction factors and also accounts for the entrance effects. The model uses the REFPROP data base where the Carnahan-Starling-DeSantis equation of state is used to calculate the refrigerant properties. The model includes the effect of various design parameters, namely the tube diameter, tube relative roughness, tube length, level of subcooling and the refrigerant flow rate. The model is validated with earlier models over a range of operating conditions and is found to agree reasonably well with the available experimental data for HFC-134a.

Flow characteristics of refrigerants flowing through capillary tubes : A review

Abstract: A comprehensive review of the literature on the flow of various refrigerants through the capillary tubes of different geometries viz. straight and coiled and flow configurations viz. adiabatic and diabatic, has been discussed in this paper. The paper presents in chronological order the experimental and numerical investigations systematically under different categories. Flow aspects like effect of coiling and effect of oil in the refrigerants on the mass flow rate through the capillary tube have been discussed. Furthermore, the phenomenon of metastability and the correlations to predict the underpressure of vaporization have also been discussed. The paper provides key information about the range of input parameters viz. tube diameter, tube length, surface roughness, coil pitch and coil diameter, inlet subcooling and condensing pressure or temperature. Other information includes type of refrigerants used, correlations proposed and methodology adopted in the analysis of flow through the capillary tubes of different geometries operating under adiabatic and diabatic flow conditions. It has been found from the review of the literature that there is a lot more to investigate for the flow of various refrigerants through different capillary tube geometries.

Performance of a domestic refrigerator under influence of varied expansion device capacity, refrigerant charge and ambient temperature.

Abstract: This paper reports experimental results of an on/off cycling domestic refrigerator at varied expansion device capacity (EDC), quantity of charge and ambient temperature. It was found that the energ ...